The present invention relates to a recording-reproducing apparatus for recording a time code signal simultaneously with a picture signal.
A conventional picture-recording unit for broadcast that is one of the recording-reproducing apparatuses applies addressing to a picture signal material to be recorded every frame cycle by recording a time code signal simultaneously with recording of a picture signal.
A time code address assigned to the picture signal material every frame cycle in accordance with the time code is used for time alignment in editing or reproducing the picture signal material.
The broadcast standard SMPTE279 applied to the above picture recording unit for broadcast describes the format of D5VTR. FIG. 2 shows a tape-like recording medium cited from the standard. The above recording-reproducing apparatus records a picture signal in a helical track 1 and moreover, records a time code in another linear track 2.
Thus, a time code recorded in another linear track 2 separately from a picture signal is referred to as linear time code (hereafter abbreviated as LTC) and the LTC is also standardized in the broadcast standard SMPTE12M. Standardization of the LTC is applied to TV systems of 30, 25, and 24 frames per sec as described in the broadcast standard SMPTE12M. These TV systems are based on the existing broadcast systems such as NTSC (and HD), PAL, and interlace TV system for a film or the like.
In the case of the interlace TV system, one frame is constituted with a first field and a second field. The NTSC uses a type of band compression transmission in which 525 lines which is a total number of lines for one screen is divided into every 262.5 lines and data is separately transmitted in two fields. In this case, though the field frequency is 60 fields per sec, the frame frequency is 30 frames per sec.
The number of TV screens per sec of the interlace system uses not the number of fields but the number of frames. Therefore, the LTC standard is also specified so that a time code is allocated in frames as described in the broadcast standard SMPTE12M.
As shown in FIG. 3 cited from the broadcast standard SMPTE12M, the relation of phases between and cycles of a synchronizing signal and an LTC signal of the 525 TV system (NTSC system) are described. From FIG. 3, it is found that an LTC cycle 7 is 33.37 ms and there are 30 time codes per sec.
A frame number indication area 3 constituted with bits of 1FRAME, 2FRAME, 4FRAME, 8FRAME, 10FRAME, and 20FRAME for expressing a frame number is present at the head of the time code waveform shown in FIG. 3.
According to the standard, as shown in FIG. 4, the value of the decimal number of a frame number is divided into the tens digit and the units digit and these digits are respectively expressed by a binary number in accordance with the rule of BCD (Binary Coded Decimal). That is, two bits are assigned to the tens digit and four bits are assigned to the units digit and thereby, it is possible to express frame numbers of 0 to 29 with these six bits.
However, the above-described conventional recording-reproducing apparatus such as a picture recording unit for broadcast has the following problems on the progress system of the non-interlace system which has been noticed as a next-generation broadcast system instead of the interlace system.
First, the progress system is briefly described below.
For example, 525P of the progress system is not a system of transmitting 525 by dividing them into two fields based on the existing NTSC system but a system of handling 525 lines every 1/60 sec as shown in the broadcast standard SMPTE293M.
Because the progress system does not include the concept of a field, 60 frames are used every second and therefore, the number of screens per sec becomes 60. That is, in the case of the progress system, it is necessary to assign time codes corresponding to every screen to picture signals of 60 screens per sec.
According to the SMPTE12M of the LTC standard, as described in Background Art, it is impossible to assign time code values necessary for one second to the progress system of 60 frames per sec in the case of the conventional LTC-signal code configuration. Therefore, it is necessary to expand the conventional code configuration to a new LTC-signal code configuration.
Moreover, the D5VTR described in accordance with the recording format shown in FIG. 2 is a digital VTR which is developed to record digital picture signals in a broadcasting station. However, the digital VTR has been more frequently used as a data recorder not only for recording digital pictures but also for mainly recording and reproducing data. Also in this case, the conventional LTC is used to control addresses of recorded signals.
However, when using the digital VTR as a data recorder, the concept of a field in picture signal data is not present in the recorded data. As a result, the concept that two fields form one frame or a time code value can be assigned only every frame gets in the way. It is rather preferable that a time code is assigned every 1/60 see that is the minimum unit of VTR record. Also in this case, there is a problem that the number of frame numbers of LTC signals becomes insufficient similarly to the case of the progress system.
Therefore, a recording apparatus corresponding to the progress system which may spread as a next-generation broadcast system and a recorder such as a data recorder have a problem that an existing time code cannot control recorded addresses every 1/60 sec which is the minimum recording unit.
The present invention solves the above conventional problems and provides a recording-reproducing apparatus capable of controlling recorded addresses in a high-accuracy minimum recording unit by using an existing time code when recording signals of the TV system and the recording system requiring recorded address control every 1/60 sec which is the minimum recording unit under recording.
To solve the above problems, a recording-reproducing apparatus of the present invention is characterized by realizing its compatibility with an existing time code, slightly changing a linear time code signal, assigning a time code corresponding to the recording minimum unit, and controlling recorded addresses.
The recording-producing apparatus of embodiment one of the present invention is a recording-producing apparatus for recording a picture signal in a helical track of a tape-like recording medium and simultaneously recording a time code signal in a linear track, in which the time code having a frame number expressed with a decimal notation is defined so as to assign three bits to the tens digit and four bits to the units digit in order to express the tens digit and units digit with a BCD notation, and the time code in which the tens digit and units digit of the frame number are expressed with the BCD notation is recorded every vertical period of the picture signal in accordance with the definition.
The recording-producing apparatus of embodiment two is a recording-producing apparatus for recording a picture signal in a helical track of a tape-like recording medium and simultaneously recording a time code signal in a linear track, in which the time code having a frame number expressed with a decimal notation is defined so as to assign six bits to the frame number in order to express the frame number with a binary notation, and the time code in which the frame number is expressed with the binary notation is recorded every vertical period of the picture signal in accordance with the definition.
The recording-producing apparatus of embodiment three is a recording-producing apparatus for recording a picture signal in a helical track of a tape-like recording medium and simultaneously recording a time code signal in a linear track, in which the time code having a frame number expressed with a decimal notation is defined so as to use a field decision bit for deciding the field of one frame thereof as a group of two fields of said picture signal, and moreover defined to assign two bits to the tens digit of the frame number and four bits to the units digit of the frame number in order to express the tens digit and units digit with a BCD notation respectively, and the time code in which the tens digit and units digit of the frame number are expressed with the BCD notation is recorded every vertical period of the picture signal in accordance with the definition.
According to the above structures, compatibility with an existing time code is made possible and a recorded address is controlled by slightly changing a linear time code signal and assigning a time code corresponding to the minimum recording unit.
As described above, when recording signals of the TV system and the recording system requiring recorded address control every 1/60 sec which is the minimum recording unit correspondingly to the systems, it is possible to control recorded addresses in the accurate minimum recording unit by using existing time codes.